ML18152A173
| ML18152A173 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 12/18/1991 |
| From: | Fredrickson P NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML18152A174 | List: |
| References | |
| 50-280-91-31, 50-281-91-31, NUDOCS 9201140076 | |
| Download: ML18152A173 (20) | |
See also: IR 05000280/1991031
Text
UNITED STATES
NUCLEAfl REGULATORY COMMISSION
REGION II
Report Nos. :
101 MARIETTA STREET, N.W.
ATLANTA, GEORGIA 30323
50-280/91-31 and 50-281/91-31
Licensee: Virginia Electric and Power Company
5000 Dominion Boulevard
Glen_Allen, VA
i3060
Docket Nos.: 50-280 and 50-281
License Nos.:
DPR-32 and DPR~37
Facility Name:
Surry 1 and 2
Inspection Conducted:
November 4-6, 1991.
Inspection Members:
M. W. Branch
Team Leader:
Scope:
J. 0. Schiff gens
J. E. Tatum
J. F. Wechs~lb~rger
P. E. Fre
Division of
SUMMARY
.Date
This special inspection was conducted to verify specific activities and
equipment modifications taken credit for to reduce the vulnerability of the
plants to Turbine Building flooding, as discussed in an October 29, 1991
licensee letter.
This inspection also reviewed interim measures taken by the
licensee as discussed in an October 28, 1991 letter ..
Results:
T~e inspection det~rmined that, based on a combination of actions taken prior
to *the inspection and completion of commitments provided during the inspection,
the items stated in the two licensee letters have or will be satisfactorily
. implemented.
Subsequent NRC inspections wi 11 review implementation of the
licensee's commitments.
9201140076 911218
ADOCK 05000280
G
ENCLOSURE 1
TURBiNE BUILDI~G FLOOD COMMITMENTS
1.
Expansion Joints
a.
Currently, th~ Circulating Wa~er.system is o~erating with fciur main
condenser outlet expansi6n jc~nts per unit that h~ve an indeterminate
service li.fe.
The primary cc~cern is whether the* remaining service
life is sufficient for the u~its to operate until the 1992 Unit 1
outage.
The licensee has pre-posed three methods to determine the
actual rem'aining service life .
.First, there. is some re:ollection that the licensee replaced
these expansion joints d~ring the 1980 time frame.
The licensee
is ~eviewing maintenance and procurement documents in an attempt
to verify this assertion.
- *
Second,. the licensee is contacting the vendor, Garlock, in* an
.attempt to determine the remaining useful service life.
Third, if one of the at:ive two methods is unsuccessful, the
licensee plans to inspe:t one of the main condenser outlet
expansion joint on .Unit 1 during .a water box cleaning. to
estimate rem~ining service life of the 8 affected expansion
joints.
'
.
The licensee committed to satisfactory verification of serviceability
by one of these t.hree methoc:s for the. four per unit not-replaced.
Circulatin£ Water expansion j-:,ints by November 29, 1991.
b.
In .additi.on, assuming the above evaluation supports current
serviceability, the licensee corrunitted to replace the four main
condenser outlet expansion j6ints during the Unit 1 refueling outage
'", scheduled for February 1992 and for Unit 2, no later than the outage
scheduled for February 1993.
For Unit 2, the licensee conmitted to
provide the basis for extending the replacements to the Unit 2
- outage.
If a review reveals that these expansion joints were
.
replaced in the 1980 time fra..e, the licensee corruni.tted to provide an
evaluation, documenting their service life beyond the Unit. 1 and 2
outages.
c.
The flow ~hields.around the 36" Circulating Water ex~~ns~on joints
wer~ not in their as~deiigne~ condition, but would be effective in
fulfilling their design fun:tion for the postulated flooding
scenario.
The licensee committed to upgrade the material condition
of the flow shields by Decem::::er 31, 1991, to include replacement of
missing bolts.
Enclosure*l
2
- d.
In addition the Service Water *system has 12 expansion joints that
were not.replaced in 196~w
These expansion joihts are not considered
as significant a contrfbutor to risk as a result of their physical
location in the piping s1stem; .that is they are connected to smaller
diameter pipes and have two isolation valves upstream of the
expansion joints.
The ~icensee colTITlitted to visually inspect these*
expansion joints by N*ovember 29, 1991. and provide a schedule for
replacement of any expa~~{on joints that warrant it.
2j
Turbine Building Sump Pumps
Based on the identified *need to further improve sump pump reliability in
order to maintain seven of nine pumps operable, the licensee committed to
develop a periodic test prosram for these pumps, to include the pumps,
level switches, check valves and power supplies.
This testing would
verify quantitative flow and operability of equipment. -The program will
be developed by December 31, 1991 with the first series of periodic tests
completed by January 31, 199Z
3.
Turbine Building Sump Backflcw Limiters
Based on inspection concerns that annual inspection without testing may
not be frequent enough to er.sure functionality of the Turbine Building
sump backflow limiters, *whi.:h are an important. part *of the flood
propagation mitigation scher..:,. the licens.ee co1T1T1.itted to develop and .
implement a testing and/or re~lacement program for these backflow limiters
by February 28, 1992.
.
.
REPORT DETAILS
1.
Persons Contacted
Licensee Employees
- W. Stewart, Senior Vice President, Nucle~r
- E. Harrell, Vice President, Nuclear Operations
- M. K~nsler, Station Manager
W. Benthall, Supervisor, Liceniing * .
- D. Benson, Manager, Nuclear Engineering
- R. Berryman, Manager Nuclear Analysis and Fuel
D. Buchett, Senior Staff Engineer, Nuclear Engineering
'*M. Bowling, Manager, Nuclear Licensing and Programs
- D. Christian, Assistant Station Manager
J ,. Downs, Superintendent of Outage and Planning
J. Graf, Supervisor, Project Engineering, Nuclear
R. Green, Supervisor, System Engineering
R. Gwaltney, Superintendent of Maintenance
A. Hall, System Engineer
D. Hanson, Supervisor, Maintenance Support
- L. *Hartz~ Mana~er, Nuclear Quality Assurante
D. Hart, Supervisor, Quality Assurance
J. McCarthy, Supertntendent of Operations
- J. Price, Assist~nt Station Manager
R. Scanlon, Senior Staff Engineer, Licensing
T. Sowers, Superintendent of Engineering
J. 'Stauffer, MDV Program Coordinator
- . R. Thomas, Nuclear Analyst
NRC Personnel
- S. Ebneter, Regi~nal Administrator, Region II*
- F. Congel, Director, Division of Radiation Protection and Emergency
Preparedness, Office of Nuclear Reactor Regulation (NRR)
- W. Beckner, Risk Applications Branch Chief, NRR
- H. Berkow, Project Director, NRR
- M. Branch, Senior Resident Inspector, Region II
- s. Buckley, Senior Project Manager, Region II
- K. Clark, Public Affairs Officer, Region II
- P. Fredrickson, Section Chief, Region II
- J. Schiffgens, Risk Analyst, NRR
- J. Tatum, Senior Reactor Engineer, NRR
- J. ~echselberger, Senior Regional Coordinatdr, Office of the Executive
Director of Operations*
- S. _Tingen, Re~ident Inspector, Region II
- Attended exit interview.
2
Other licensee * technical staff rr:-embers we.re contacted during * the
inspection.
2.*
Background
On August 30, 19.91, Virginia Electric and Power Co. submitted an
Individual Plant Examination (IPE) on Surry, in response to Generic Letter 88-20, "Individual Plant Examination for Severe Accident Vulnerabilities".
This Generic Letter stated that 1icensees of existing plants should
perform a systematic examination,. IPE, to identify any plant-specific
vul nerabil i ti es to severe acci der.ts and report the results to the
Commission: * The internal events portion of the IPE, excluding internal
flooding, resulted in a point estimate core damage frequency (CDF) of.
, 7 .4E-05 per .reactor year.
CDFs of this magnitude are not unusual.
However, the internal .flooding portion of the li.censee's IPE analysis,
which yielded a point estimate CDF of l.lE-03 per reactor year, identified
internal flo.oding as a vulnerability.
The NRC staff ag_rees that a CDF of
this magnitude is unusual and indicative of a signjficant vulnerability.
The licensee's analysis showed that the most important flooding sequences
result from failures in the gravity fed, Circulating Water (CW) and*
connecting Ser~ice Water (SW) sys:ems in the Unit 1 or Unit 2 Turbine
. Buildings which cause flooding in :he Emergency Switchgear Room (ESGR) and
the subsequent loss of A~, and eventually DC, power.
The flow rate into
each of eight, 96 inch diameter C-" pipes at the intake is about 190,000
gpm during normal operation-. .
The identified sequences, similar: to
unrecovered station blackout sequences, are responsible for about 90
percent of the total internal flocding CDF.
The unique design feature of SurrJ* responsible for its vulnerability to
internal flooding is the location of the ESGR off the lowest level.of the
Turbine Building, 20 feet below the level of the intake canal.
- Consequently, breaks in CW or S\\.i pipes or equipment which cannot be
isolated by closing a~propriate irtake or isolatibn valves, and leak more
water into the turbine Building than its sump pumps can remove, which is a
total of about 9,100 gpm, would, in the absence of mitigativ~ measures,
lead.to core damage.
The licensee, while acknowledging that this vulnerability is real, also
believes the CDF estimate is v.ery conservative.
In a letter dated October
28, 1991, the' licensee presented a schedule for planned, internal flo6ding
related modifications, proposed. 7'urther discussion. of its ongoing
reanalysis of internal floodihg, and stated the following:
11 In the interim, Virginia Ele::tric and Power Company will augment the
present shift coverage of pctential flood areas with a dedicated
flood watch for those areas.
The* dedicated flood watch would *
specifically be observing internal flood~importani valves, pip~s, and
. expansion joints on. a contir.uous basis for early indications of
1 eakage or other degraded ;:,erfonnance.
Furthennore, as an
enhancement to flood mitigation capabilities, administrative controls
wi 11 be added, on an i nterirr. basis, to reql!i re opera bi 1 ity of a 1l
3
nine sump pumps to further increase expected availability.
in the
event of a sump pump being jnoper.able, priority will be given to
prompt restri~ation of the pu~p to an operable condition.
Finally,
procedures for installation of stop logs at the high level intake
will be forma 1 i zed and the resources ( both material and personne 1)
reqtiired for installation will be identified and dedicated to ensure
the most timely action possible tri the* use of stop logs for flood
mitigation.
11
1~ a letter dated Octobe~ 29, 1991,.the licensee discussed its reanalysis
aimed at better understanding the internal flooding issuei and obtaining a
more realistic* CDF.
In this letter, the licensee stated that reanalysis
yielded.a CDF of l.7E-04 per reactor year, taking into account specific
equipment changes that had not been_ considered in the initial analysis and*
additional modifications resulting from the IPE identification of the
internal flooding vulnerability.
Accprding to the October 29 letter, the
following items have been factored into calculation of a reduced CDF for
inter~al flooding:
a)
~)
c)
"Expansion joints on the Circulating Water and Service Water
systems and associated MOVs, which are significant contributors
to any flood damage state frequency, have recently been
replaced.
11
_
"Inspections on MDV bolting have recently been completed.-
(MOV
bolt failure was considered a significant initiating event in
the original IPE analysis.)"
.
11A -minimum of seven of nine turbine building sump pumps are
being maintained operable."
The NRC believes that, if satisfactorily implemented, the above actions
and interim measures will reduce the risk to internal flooding.
This
inspection. was to verify statements a), b), and c) in the October 29, 1991
letter and to review the interim measures taken by the licensee discussed
in the October 28, 1991 letter.
3~
Systems Descriptions--Turbjne Building
a.
The CW System draws water from the James River to provide cooling water
for the main condensers and to provide water for the SW System.
The eight
CW* pumps discharge into* a common; one and one-half mile long,
concrete-lined intake canal that directs CW to the station area.
The High
Level Intake St~ucture on each unit di~ects the watet into four concrete
pipes.
For maintenance purposes, i.e. with th~ relevant portion of the CW
System in a maintenance configuration, isolation of flow at this point can
be made by the insertion of large plates (4 per pipe) called stop logs.
The concrete pipes connect to* four buried 96 inch diameter steel pipes
that. carry water from the concrete pipe to the individual condenser
half-shells in the Turbine Building.
Condenser inlet flow is secured by
fo~r butterflj motor operated valves (MOVs). In addition, each inlet line
contains Jn expansion joint do~nstream of the inlet MOY, which allows .for
settling of system* components after installation without putting*
unacceptable stresses on the piping. ** Each condenser half-shell has two
tube bundles.
Water leaving*each tube bundle flows through a 96 inch
outlet line, two expansion joints and another butterfly MOY isolation
valve.* Tbe four outlet lines tie* into a discharge tunnel which also
receives SW System flow~
The discharge tunnels from both units go to the
- common discharge canal, which returns the water to the James River.
b *. Service Water System
Th.e SW piping taps off the CW intake piping in the Turbine Building
between the High Level Intake Structure and the condenser inlet MOVs.
Gravity provides the motive forc.e for the .flow of the SW to the various
loads an*d subsystems of the SW System.
The SW System supplies cooling
. water through th~ plant with several supply headers, which can be isolated
by hand operated valves or MOVs.
The Bearing Cooling Water. Sys tern and the
Ccimponent Cooling Water System are the main systems that use SW in the
Turbine Building (36" and* 42" lines, respectively).* Both contain SW water
butterfly isolation MOVs and expansion joints..
Return headers collect
'th~ SW from th~ cooled com~onents and. subsystems and return the water to
the James.River via the Discharge Tun~el and the Dischijrge Canal.
c.
Condenser Flood C~ntrol Subsystem
The purpo~e of the Condenser Flood Control Subsystem is to alert the
operator through alarms that flooding is taking place in the Turbine
Building that could impair safety-related equipment.
This subsystem
. allows the operator some period of time, depending on the severity of the
flood, to isolate the source of the flboding after receipt of the first
alarm before the condenser C~ inlet valves are automatically closed.
The
system consists of six level sensing *detector assemblies, three for alarm
and three for CW valve-closing.
The alarm*.assemblies are located in both
the condenser and amertap pits.
The isolatioh assemblies are mqunted 9"
off the Turbine Building floor.
This system also contains associated
. alarm circuitry, and a control system using a redundant matrix to initiate
automatic closing of the associated condenser CW inlet valves.
4.
Replacement of CW System and SW System MOVs
a.
Description
During the approximately one year period between May 1988 and July 1989,
the licensee replaced the following MOYs in the SW and CW Systems on both
Unit 1 (100 series) and Unit 2 (200 series):
100A,B,C,D/200A,B,C,D
Condenser Waterbox Outlet
Isolation Valve (96")
101A,B/201A,B
102A, B/202A, B
103A,B,C,D/203A,B,C,D
106A,B,C,D/206A,B,C,D
5
Bearing* Cooling Water Heat Exchanger fol et.
Isolation Valve {36")
Comp.:inent Coolin9 Heat Exchanger Inlet
Isolation Valve (42"/10") *
Recirculation Spray Heat Eichang~r Inlet
Isolation Valve {30")
Con~enser Waterbox Inlet Isolation Valve
(96")
Except for the condenser waterbox outlet isolation valves (100/200), these
are the first isolation valves in the CW and SW systems and there ar~ ~o
expansion joints upstream of these valves.
b.
Problem History
. The original recirculation spray heat exchanger inlet isolation. valves
(103/203) were aluminum bronze butterfly valves and they were replaced
with butterfly valves of the sarrie material that were designed to provide
better s~at tightness.
The origi~al valves were leaking sw* through th~ir
seats and allowing hydroid growtr. formation and fouling of the heat
exchangers. * The other va 1 ves ( lCJ/200, 101/201, 102/202, and 106/206)
were replaced in .response to NRC Information Notice 84-71, "Graphitic
Corrosion of Cast Iron in Salt wc.ter,
11 to eliminate graphitic corrosion
problems.
The original valves were cast iron butterfly valves and over
time graphitic corrosio11 would have reduced the strength of these valves,
. so they were replaced with ductile iron butterfly valves.
c.
Valve Replacement and Design Review
The inspectors* reviewed the foll O'fl'ing documents to verify the adequacy of
the valve replacement activities that were.previously completed:
NUS 2074
DC 86-10
DC 86-11
DC 85-17
_DC 85-18
Specification for Motor-Operated Butterfly Valves for
Service Water and Circulating Water Systems (Rev. 1)
Servite Water and Circulating Water Butterfly Valve
Replacement/Surry 1
Service Water and Circulating Water Butterfly Valve
Replacement/Surry 2
Service Water ~otor Operated Butterfly Valves Surry 1
Service Water Motor Operated Butterfly Va 1 ves Surry 2
These valves were designed to withstand at least 50 psi normal operating
pressure whereas the no~inal syste~ operating prissure was about 9 psig.
The.valves were also designed for a maximum differential *pressure of 20
6
psig; the worst-case pipe break would result in a maximum differential
pressure of about 10 psig.
d.
Current Practices
The licensee monitors valve performance by cycling the valves quarterly
per the ASME Code in accordance with the following procedures:
. 1-PT-25 .1
2-PT:.. 25.1
Quarterly Testing of Circulating Water and Service
. Water System Valves
Quarterly Testing of Circulating Water and Service
Water System Valves
Local and remote valve~ position is* verified per the ASME Code each
refueling outage by the following procedures:
1-PT-18. lOP
2-PT-18. lOP
Verification of Local and Remote Valve Position
. Indic~tions in.the T~rbine and Servite Buildings
Verification of Local and Remote Valve Position**
Indications in the Turbine and Service Buildings
Valve seat leakage is_ monitored each refueling outa.ge by the following
procedures:
. 1-0PT-CW-001
Lea~ Test of the Circulating Wate~ Inlet and Outlet
9611-Valves
2-0PT-CW-001
Leak Test of the Circulating Water Inlet and Outlet
96
11 Valves
l-OPT-SW-001
Leak Test of SW Valves 1-SW-MOV-lOlA and
1-SW-MOV-lOlB
2-0PT-SW-001. Leak Test 6f SW Valves 2-SW-MOV-lOlA and
2.-SW-MOV-lOlB
1-0PT-SW~002
2-0PT-SW-002
Leak Testing. of Component Cooling Water Heat Exchanger
Service Water .Valves
Leak Testing of Service Water Valves
2-SW-MOV-202A and 2-SW-MOV-2028
. e.
Conclusion and Recommendations
Based on a review of the information discussed above, the inspectors
concluded that the replacement of CW and SW System valves in conjunction
with the current* practices of. monitoring valve status and perfonnance
provide an increased level of assurance that: (1) the CW and SW isolation
valves will be maintained intact, and (2) the CW and SW isolation valves
will be capable of isolating a flooding event. The inspectors.did identify
7
that, although* these valves are in the MOV Program, the licensee should
con-sider including these MOVs as part of the station Reliability-Centered*
Maintenance Program
5.
Valve and Fastener Inspection
a.
-Description
In order to minimize the risk of flooding in the Turbine Building, the
licensee performed.a visual inspection of CW and SW System valves.which
serve to isolate the high level intake canal.
The accessible parts of the
valves and exposed adjacent piping were inspected for general pressure
boundary integrity including bolt engagement and condition, condition of
expansion joints, integrity of connecting bolts for the valve operators,
and overall general condition. The following valves (and adjacent piping)
from both Unit 1 and Unit 2 were included in the inspection:
100A,B,C,0/200A,B,C,O
101A,B/201A,B
102A,B/202A,B
103A,B,C,D/203A,B,C,D
106A,B,C,D/206A,B,C,D
Condenser Waterbox Outlet Isolation
Valve (96
11
)
Bearing Cooling Water Heat Exchanger Inlet
Isolation Valve (36
11
)
Component Cooling Heat Exchanger Inlet
Isolation Valve (42
11/10
11 )
Recirculation Spray Heat Exchanger Inlet
Isolation Valve (30
11
)
Condenser Wat~rbox Inlet Isolation
Valve (96
11
)
Several other SW valves were also included in the inspection.
b.
Inspection Basis
The licensee's inspection was not based on site-specific problems that had
been experienced previously at Surry, but rather the inspection was based
on industry experience in general.* Excessive corrosion and degradation of
fasteners, valve bodies, and piping; inadequate tensioning of fasteners,
and fatigue failure of fasteners used to secure valve operators in place
have resulted in piping system transients and failures.
c.
Inspection Results
The licensee documented the resu1 ts of the inspection in a memorandum
dated October 7, 1991.
The following discrepancies were identified:
a.
The amertap barrel upstream of 1-CW-MOV-1000 (4- bolt flange)
was missing one bolt.
b.
The amertap barrel upstream rif 2~CW-MOV-iOOA had one nut out of
a~proximately 80 cross-:~~eaded.-
c .. All of the flow shields around expansion Joints upstream of
1/2-CW-MOV-lOOA,B,C,0 ar.d -200A,B,C,D did not have the bottom 10
to 20 bolts installed ~~ich caused a gap to exist between the*
pipe and expansion join~ shield in excess of one irich.
-The inspecto~s reviewed the inspe:tion results and not~d that, although
th~*inspection appeared to be -adecuately implemented, the licensee did not
have a for_mal procedure for perfonning the in*spection.
The licensee is
currently developing a procedure for inspecting CW and SW bolted
connections.
Maintenance. requests were submitted on these deficiencies
and several were corrected prior tci the inspection team .arrival *. *
Inde~endent of the licensee's effort, the inspectqrs selectively inspected
some of the CW and SW fastners and valves and made the following
observa hons:
a.
The
expansion joints . downstream of 1-SW-MOV-103C
and
. 2~SW-MOV-203A had faste~ers *contacting the rubbei expansion joint.
b..
The expansion joints do'f'l*:--,stream of 1-SW-MOV-103C&D had been
nicked and gouged in places.
d.
Conclusion and Recommendations
The inspectors concluded that the licensee.
1s valve and fastener inspection
provided an increased level of assurance that the equipment that was
inspected would co_ntinue to provice the pres*sure boundary integrity it was
designed to provide.
However,
the inspectors did identify some
discrepancies, as dis.cussed above, that were not identified by the
licensee.
The licensee's inspect.ion procedure w_hich is cufrently being
developed
should include consiteration for such discrepancies.
Additionally, the licensee is expected to teview the specific observations
identified by the NRC and resolve them accoraingly.
a
6.
Expan~ion Joint Replacement
a.
Description
The expansion joints are used to a1low for the thermal expansion of the CW
and SW piping systems.
In addition to thennal expansion, the expansion
joints permit ease of maintainability of the butterfly valves in the CW
and SW systems.
The expansion joints va*ry in size from 96
11 diameter for
the CW system to 42
11
, 36
11
, 30
11 ar.d 10
11 diameters* for the SW system.* The
expansion joints are concentric s~ool type rubber joints with galvanized
retaining rings.
The compositior of the rubber joints, as specified* in
the original ~pecification (NUS-32, revised July 3, 1969), is essentially
synthetic rubber.
A more recent specification (NUS~2076, dated December
16, 1987), describes the materia~ as EPDM (ethylene propylene diamine .. *
rubber) and polyester.
The licer.see indicated that NUS-2076 was used to
9
procure the expansion joints for the MOV and expansion joint maintenance
conducted in 1988 (see paragraph 4).
The expansion joints function in
brackish, untreated~ river water and are considered nuclear safety related
com*ponents.
As a result of an earlier study on internal flooding, the _
licensee installed flow shields around the circumference of the 96" CW
- system, expansion joints. The purpose of the shields is to limit the flow
from an expansion joint should it fail.
b. * History of Replacement
In reviewing the CW and SW expansion joints, the 1nspectors reviewed the ..
status of the ,2 expansion joints that the licensee determined can cause
Turbine Building flooding.
Thirty-two of these expansion joints had been
- replaced in 1988.
The remaining. 20 expansion joints comprise 8 main
condenser outlet expansion joints in the CW system and 12 expansion joints
, in the SW supply to the bearing cooling water heat exchangers.* The
following list identifies these 52 joints:
- Description
Number EJ Replaced
Total EJ's
REJ-2: 96
11 (CW).
8
.8
REJ-3 & 4: 96
11 (CW)
8*
16
REJ-7: 42"(SW to
2
2
c'omponent cool i_ng)
REJ-8: 36"(SW to
4
4
bearing cooling)
REJ-5: 30"(SW to
0
12
bearing tooling)
REJ-6: 30"(SW,to
8
8
component cooling)
REJ-16: lO"(SW pump)
2
2
Totals:
32 EJs replaced.
52 EJs
The inspectors questioned the apparent discrepancy between the October 29,
1991 letter, in which the licensee stated that expansion joints that are
"significant contributors" to flood damage had been replaced and the fact
that several important expansion joints had not been. replaced.
The
licensee stated that these not-replaced expansion joints were not
significant, but initially did not provide a documented technical basis
for this determination.
P.ending .receipt of this evaluation, the
inspectors decided to review the material condition of the not-replaced
expansion joints. Later in the inspection period the licensee provided an
evaluation memorandum dated November 6, 1991, stating that the *
'
!
10
not-replaced expansion .joints were not
11significant contributors" in that
they are located sighificantly downstream of the first CW or SW isolati_on
valve.*
Although these expansior. jofots .were not .considered as
"significant contributors
11
by the licensee, the *inspectors* and the
l ice.nsee determined that their importance was s i grli fi-cant enough to
warrant inspection and evaluation for serviceabil!ty.
c. Present Status
The service life of the not-replaced expansion joints has exceeded the
vendor's recommendations and an engineering evaluation for extending the
life of these expansion joints has n*ot been*conducted by the licensee.
NUS-38 specifica~ion indicated that the .servic.e life for the original type
of expansion joint was about 15 to 17 y~ars whil~ NUS-2076 iMdtcates for
that particular materfal specified, the expected service life would be
- about 8 to 10 years.
The licensee ini.tiated discussions with the original
manufacturer who indicated that the useful service life may bt extended *
due to the mild service condition experienced for the specific CW system
installation at Surry.
T~e inspectors*also reviewed the installation of the flow shiel~s on the
C\\./ system.
The inspector's review as* well as two previous licensee
inspections found missing bolts and gaps between the shield and the
mounting flange.
On October 7,. 1991, the systems engineer and a VT-2
piping whi~h included the ~xpansion joints. Results of these inspeftions
are discussed further *in paragraph 5 of this report.
Between October 30
and November 2, 1991, Quality Assurance conducted an assessment of the.
flood protection p_rogram and compensatory actions.
The original analysis
assumed a uniform 1/2 inch gap around the flow shield, but in the actual
installation the gap ~aries. * In some locations the gap may be as large as
1 to 1.5 inches wide.
The inspectors questioned, assuming a uniform 1
inch gap, if this would significantly effect the flooding analysis.
Through discussions with the licensee and by reviewing the original
flooding analysis, .the inspectors determined that the flow shield*
restricted flow would increase from approximately 16,000 gpm to about
32,000 gpm.
The 1 icensee contends that this would not significantly
effect the overall CDF ..
The inspectors reviewed procurement documentation to determine if any
significant failures had occurred in the past. Maintenance histories were
not specifically kept in the past at th~s component level. Apparently an
expansibn joint (REJ-5) was replaced in the SW outlet line to a bearing
cooling water heat exchanger.
This occurred in July 1985.
A procurement
document indicated that a 96
11 condenser distharge expansion joint (REJ-4)
was also replaced in June of 1987.
T.he documentation did not clearly
indicate a specific failure mechanism.
No definitive conclusions on
expansion joint maintenance or failure could be drawn from these
replacements.
11
.The inspectors examined a Goodall 36
11 expansion joint in the warehouse an*d
verified that ex~ansion joints. were bejng properly stored in. a dark, dry
location. _ This particular expansion joint did not hav.e- a "filled arch
11
The
11filled arch
11
- expansion joint is generally used in safety related
systems in horizontal applications.
In this appli~ation the
11filled arch
11
prevents debris buildup in the arch ~hich could restrict free movement of
the expansion joint.
The inspectors were concerned that this expansion
joint could be inadvertently installed in a safety related system.
The
licensee agreed to review this* and ens*ure that the expansion joint would
only be used in the intended application.
The inspectors questioned the licensee with regard to testing and
installation of the expa~sion joints.
Hydrostatic testing was conducted
- for the expansion joints by the supplier of the .joints. The* inspectors
reviewed some hydrostatic test reports and NUS-2076 to verify that the
joints were tested at 1.5 timei the maximum design pressure and at the
specified v~cuum pressure.
NUS-38 specifies a maximum design pressure of
40 psig and NUS-2076 lists a maximum design pressure of 80 psig for*the
96
11
expansion. joints.
The operating pressure of the system is
approximately 9 psig with the d_esign maximum operating pressure of 20
psi g.
The inspectors* al so reviewed the o*es i gn Change Package ( DCP)
"."
86.;.11-2 to ensure proper installation methods were specified and* followed.
The licensee installation piocedures were faun~ .to be adequate, including
the requirement to tighten the bolts and nuts in a uniform star pattern,
achieving uniform gasket compression and developing the required bolt.
torque in a minimum of three steps.
Testing and installation practices
were adequate._
The licensee has not yet formerly developed a maintenance program for the
expansion joints.
The inspectors questioned the licensee with regard to
the basic maintenance program elements and time of implementation.
The
- major effort of the program will involve a visual inspection of the
expansion joints.
The licensee indicated the visual inspection will
- i nvo 1 ve examination to determine if any significant off set has occurred,
dry rot, cracks, abrasions, cuts, leaks or other signs of mechanical
damage.
It is anticipated that this inspection.of the expansion joints of
concern wi 11 be conducted on an annua 1 or every refueling outage basis.
Specifics of the program have not been filia 1 i zed, but the l i c*ensee did
indicate that a visual *inspection would be conducted during the next
outage. * Based on the* results of the periodic inspections* the licensee
will determine if any expansion joints should be replaced.
Irt addition
the licensee anticipates having the expansion joint manufacturer measure
the expansion joint configurations and fabricate expansion joints to the
precise measurements to account for any slight_ misalignments that may
exist.
These are some of the considerations for the ne~ program, but the
_ specifics have not been finalized by the licensee.
Recently, the licensee has begun injecting hypochlorite in the SW system
to achieve 10 ppm chlorine concentration.
The purpose is to reduce the
amount of fouling that occurs in the springtime_ in the SW system.
The
inspectors wanted to ensure the licensee had adequately evaluated any
12
- effect the addition* of hypoch'i:rite might have on the expansion joints.
The l~censee had conducted an engineering evaluation of the effect on the
material.
This evaluation cetermined that non-metallic materials
_ indicated satisfactory perforr..ance after exposure to chlorine water
treatment.
The inspectors we'"e satisfied that this question had been
appropriately addressed.
d.
Commitments and Recommenda:ions
Currently, the CW system is c;erating with four main condenser outlet
-* expansion joints per unit tha: have an indeterminate. service life.
The
primary concern is whether the remaining service life is sufficient for
the units to operate until the 1992 Unit 1 outage.
The licensee has
proposed three methods .to dete_;.:iine the actual remaining service life.
First, there is some reccllection that the licensee replaced these
expansion joints during ~he 1980 time frame.
The licensee is
reviewing . maintenance anc procurement documents in an attempt to
verify this assertion.
Second, the licensee _is ccntacting the vendor, Garlock, in an attempt
to determine the remainin; useful service life.
Thi~d~ if one of the abo~e two methods is unsuccessful, the licensee
plans to inspect one of t~e main condensef outlet expansion joints on
Unit 1 during a wate~ b6x cleaning to _estimate remaining setvice life
of the 8 affected expansicn joints.
The licensee committed t_o satisfactory verification of serviceability by
one of these three methods for the four per unit not-replaced CW expansion
joints by November 29, 1991.
.In
addition,
assuming
the above
evaluation supports current*
serviceability~ the licensee ccrTTTli t ted to rep 1 ace the four main condenser
outlet expansion joints durin; the Unit 1 refueling outage scheduled for
February 1992 and for Unit 2, no later than the outage scheduled for
February 1993.
For Unit 2., tr:e licensee coiranitted to provide the basis
for extending the replacements to the Unit 2 outage. If a review reveals
that these .expansion joints were replaced in the 1980 time frame, the
licensee conunitted to provide an evaluation, documenting their service
life beyond the Unit 1 and 2 outages.
The flow shields around the 95" CW expansion joints were not in their
as-designed condition, but, as discussed above, would be effective in
fulfilling their design function for the postulated flooding scenario.
The licensee committed to upgrade the material condition of the flow
shields by December 31, 1991, to include replacement of missing bolts.
In addition the SW system has 12 *expansion joints that were not replaced
in 1988.
These expansion joints are not considered as significant a
contributor to risk as a* result of their physical location in the piping
! **
13
system; that is they are 1 connected to smaller diameter pipes and have two
isolation valves upstream of the expansion joints.
The licensee committed
. to visually- inipect these by November 29, 1991 and provide a schedule for*
replacement of any expansion joints that warrant it *.
The SW system has no flow shields installed. The licensee stated ;~_their
October 29, 1991 letter that the flow shields will be installed on 6 SW
expansion joints in the- SW supply 1 ines to bearing and component .cooling
by November 22, 1991. * The inspectors identified that the licensee needs
to ensure that these flow shields are properly installed;
e.
Conclusion
The inspectors concluded that. through the combination of *inspection,
remaining service life determinati.on and replacement when required, the
licensee has improved t.he reliability of the SW and CW expansion joints.
7.
Turbine Building Sump Pump (TBSB) Improvements
a.
Description
The Turbine Building Sump and Floor Drain Subsystem is composed of the
three sumps; with three sump pumps for each sump; and the associated
.
valves, instruments and piping.
The major components are the sumps .and
the sump pumps.
The Unit 1 sump is called floor drain sump number 1.
The
common sump between Unit 1 and Unit 2. is referred to as floor drain sump
number 2.
The Unit 2 sump is floor dr_ain SUlf!P number 3.
The sumps
receive floor and equipment drainage from components in the Turbine
- Building and some areas of the Service Building.
The sumps are
approximately 12 fe~t wide, 12 feet long, and 8.5 feet deep.
Each sump
has metal plate covers for access, -as necessary.
The
three-per-sump. high volume
(1300
g~m)
sump pumps
operate
automatically, based upon signals from sump level switches.
The tombined
discharge of the three pumps for each sump is directed to the Yard Drain
System, which empties into the discharge canal.
The Turbine Building sump*
pumps discharge through individual check and isolation valves to prevent
reverse flow and to permit isolation of a pump, respectively._
b. Performance History
The TBSPs are not designed as-safety related components.
Therefore, there
are no safety related electrical power supplies, nor is there built-in
redundancy of equipment or control circuits.
Because of the system* s
initial design there are several ways that the system could become non-
functional.
For example the failure of the single sump level switch for*
the 36 inch pump shutoff could render a 11 three pumps for that sump
Additionally, the failure of a single pump discharge check
- valve could result in bypass flow, back to the sump, of the other two
pumps for that sump.
'
\\
I*
14
The inspectors reviewed the following infonnation in order to assess the
.reliability of the TBSPs:*
Maintenance History
.* Reliability Information
Planned Changes to Improve Re 1 i ability
Spare Parts Management
Testing
Control Circuits and Power Supply Reliability
, Attendant Equipment
The inspectors reviewed a compu~er printout of the TBSP maintenance
history.
The printout covered the period from 1985- when the history
program was established to the present.
The TBSP history covered the
attendant equipffie~t such*as the level switches and the discharge check
valves since those items did not have unique identifiers assigned.
The
history indicated that all of the nine pumps and associated equipment have
experienced frequent fai.lures.
The inspectors discussed the TBSP pas_t
reliability with the mainten*ance PM coordinator and the system engineering
. supervisor.
c.
Present Status
When the inspectors arrived on site, the only inspection and testing of
the TBSPs was a review of switch and breaker ~osition per Operational
Checklist OC-47, dated October 29, 1991.
This procedure required the
.administrative maintenance of 9 out of 9 TBSPs operable, as initially
stated in the licensee's October 28, 1991 letter .. ' If the operators
determined that less than* 9 of 9 were operable, the procedure required*
immediate attention to initiate pump repair.
This reliability level was
changed to 7 of 9 by the licensee's October 29, 1991 letter.
Based on the
non-safety related status of these pumps and their relatively high failure
rate, the inspectors determined that this procedure was insufficient to
ensure that TBSP reliability could be maintained at either the 9 of 9 or 7.
of 9 level as stated in the licensee's October 28 and 29 letters.
The TBSPs, level switches,* and discharge check valves ar~ not currently in
the
PM program, nor are the TBSPs covered by the licensee's
Reliability-Centered Maintenance Program.
However, the motors have been
in the PM program since 1986.
Additionally, the level switches, check
valves, and the pumps are not periodically tested to verify performance.
A 11 nine pumps were tested during the period between October 3, and
November 4, 1991, and pa_ssed the* criteria established.
MDAP 0009
specifies frequency of predictive testing and provides program guidance.
The actual controlling instruction is provided by a computer based program
that specifies frequency of testing.
15
The check valves and level switch history is* not completely weil known
since there. is no unique identifier assigned to this equipment arid the
failu*re history of the breaker protective devices is .not known.
In
addition, the power supplies for the TBSP motors are located at an
elevation where flooding could result in a loss of power to the motors.
The warehouse supply of spare parts is limited and currently consist of
the following: 1) three impellers, 2) bearings and seals for approximately
three pumps, 3) two pump shafts, 4) no motors, 5) no pump casings, and 6)
no. level switches.
The licensee did however indicate that some spare
parts are on order and some are stored at North Anna.
, d;
Corrrnitments and Recommendations
Based on the inspectors' evaluation that the licensee's actions to improve
sump pump reliability were insufficient to maintain seven of nine ~umps
operable, the_ licensee committed to develop a periodic test program for
these pumps, to iric l ude the pu'mps, . level switches, check valves and. power
supplies.
This.testing would verify quantitative flow and operability of
equipment.
The progr_am will be developed by Deceml;>er 31, 1991 with the
first series of periodic tests completed by January 31; 1992
Th.e inspectors also identified that the licensee needs to consider
including the TBSPs and *related equipment in the Reliability-Centered
Maintenance Program.
In addition, the *inspectors determined that the
licensee should place more emphasis on improving parts staging for sump
pump repair.
e.
- Conclusion
Based on the above, the ins~ectors verified that the licensee has placed
addition a 1 emphasis on improving the re 1 i ability of the TBSP.
However,
without a~ on-going PM and testing program, the inspectors did ~ot believe
that the degree of TBSP reliability stated in the October 29, 1991 letter
could be assured.
After complete implementation of *the licensee
corrnnitments in this area the licensee-stated TBSP reliability should be
realized.
a~
Turbine Building Sump Backflow Limiters
a.
Current Status
Although not specifically addressed in the October 28 or 29, .1991 letters,
an important issue involving Turbine Building sump backflow limiters was
identified during the inspection~
Through reviews of the drawings
associated with the Turbine Building sumps the inspectors determined that
Turbine Building sumps receive floor drains from several adjacent areas
that contain safety related. equipment.
The areas involved included the
Unit 1 and 2 ESGR as well as Mechanical Engineering Room (MER)-3, MER-4
and the Unit 1 and 2 cable vaults.
Thrbugh the floor drain system Turbine
Building flooding could communicate with the other areas and possibly
16 .
incapacitate safety related equipment.*
The licensee has installed
- back-flow* limiters in the floor drains in the areas above.
The backflow
limiter resemble a rubber float that checks flow into the room.*. The*
inspedors performed a visual inspecti*on of the backflow limiters in MER-3
arid the ESGRs for Units 1 and 2. * The three backflow limit~rs in MER-3
appeared to be clogged with debris. and non-functional.
The backflow
limiter in both the Unit 1 and Unit 2 ESGR were cov~red with water .and.
there was also a_ large amount of debris in those sumps as well.
The
inspectors' review of the recent test of the backflow limiters revealed
se~eral problems.
First, .the backflow limiters in the ESGRs and the cable vaults for both
units had been tested per STP-70.4, Flood Protection Floor Drain Back**
Water Sewer Stop Valve Operability Test, dated February 20; 1990.
This
procedure is an annual test and base~ on review of past test results and
discussions with plant personnel, the inspectors* determined that the
back fl ow 1 imi ters do not meet test criteria every time the test i.s
conducted.
Second, the backflow limiters in MER.,.3 and MER-4 are not periodically
tested and* based on the condition observed by the inspectors are not
routinely maintained. * The licensee indicated that the backflow devices in
. th~ two MERs are not easily tested Since there is no adjacent standpipe to
allow back ftll of -the Arain system.
b.
Conclusion and Corrmitments *
The inspectors consider that annual inspection without testing may not be
frequent enough to ensure functionality of the backflow limiters which are
an important part of the flood propagation mitigation scheme .. Based on
the inspectors' concerns the licensee replaced the backflow limiters in
MER-3.
In addition the inspectors questioned the accepta~ility of current*
testing methods and frequency for the backflow limiters in the Unit 1 and
2 ESGRs and cable vaults.
Based on these concerns, the licensee committed
to develop and implement a* testing and/or replacement program for these
backflow limiters by February 28, 1992.
With this program, the inspectors
consider that the Turbine Building sump backflow limiters should be
maintained in an operable condition.
9.
Interim Miasures
In their October 28, 1991, letter, the licensee committed to several*
interim administrative.measures to reduce the risk .of.*plant damage due to
internal flooding~
An important note is that these measures are no1;
included in the actions necessary to reduce the CDF.
The inspectors
reviewed the implementation of two specific interim measures; dedicated
flood watch and proced~ral controls for stop log installation.
- . . ~- ..
17
.
. .
a.
Dedicated Flood Watch
The flood watch patrol was initially implemented by utiliiing the existing
fire watch in thi area.
This resulted in a dil~tion of the individual's;
ability to perform either function *well. !he inspectors *discussed this
concern with station management and a dedicated flood watch was
established and procedures were developed.to implement*this interim
administrative control.
Procedure GMP~012, Roving Flood Watch
Responsibilities, dated*October 21, *1991, was issued.
This procedure
specifie*d the level of training required, the equipment* necessary, the
vulnerable equipment, and the route to foll ow.
The inspectors verified
adequate implementation of this interim action by interviewing several
flood watches, as well as witnessing several of them performing their
duties.
h.
Procedur~l Controls for Stop Log ~nstallation
The inspectors also verified that the commitment- to proceduraliie stop log*
. installation was also implemented. Procedure GMP-011, Installation and
Removal of Stop Logs, dated November 1, 1991, was reviewed.
This
procedure ensures that equipment is prestaged and that personnel are
._
trained to perform the task.
The procedure instructs the mechanics to
attempt to install the four logs* per intake bay and, if problems are
encountered, *they are to request assistance from the Station Emergency
Manager or the Technical Support Center, if manned:
.
.
It should be noted that under high flow condiiion~, talculations indicate
that the stop logs may not be able to be inserted.
Additionally, the
station did not test the ability to insert the stop logs under flow
conditions.
However, they did review previous stop log installations foi
maintenance purposes and factored that experience into the new stop log_
procedure.
10.
Exit Interview
Th~ inspection scope and results were summarized on Novemb~r 6, 1991, with
those individuals -identified by an asterisk in paragraph 1. Specifically,
the
recommendations and conclusions from paragraphs 4.e, 5.d, 6.d and e,
7.d and e, 8.b, and 9 were discussed with the licensee. The licensee
- acknowledged the inspection conclusions with no dissenting comments and
provided the corranitments as discussed in the above paragraphs.
The
licensee did not identify as proprietary any of the materials provided to
or reviewed by the inspectors during this inspection.